FR2641926A1 - IMPROVED GRAPHIC SYSTEM TELESERVER - Google Patents

Abstract

Teleserver system allowing to receive high definition "images". The videotex receivers T1, T2 are connected to the digital ISDN network. On this network, videotex servers SV1, SV2 and image servers SG1, SG2 are connected. By calling a videotex server by the conventional procedure, it is also possible to receive the images from the associated image server, by a channel of the ISDN network in transparent mode.

Description

IMPROVED GRAPHIC SYSTEM TELESERVER

  The present invention relates to a teleserver system for transmitting graphics, particularly

images, improved quality.

  The téléserveurs systems know a very important development, in particular in France, by the system exploited under the mark TELETEL. In such a system of terminals & display screen called MINITEL can access (initially) by normal telephone lines & hosts. With the help of identification numbers, each holder of a terminal can access databases managed by different service providers. The specific billing is done for some call numbers from the number called by the terminal holder depending on the connection time to the host. By this means it is possible to connect to servers of very different natures that go from the directory

  telephone to video games.

  One of the limitations of this system lies in the fact that it is not possible to transmit to the terminal a graphic, for example an image, having a good definition and a good graphic quality. This is due to the limitation of the information transfer rate imposed by the static switched telephone network which is of the order of 1200 bauds. However, it appears that in many cases the possibility of transmitting a graphic quality would be a very significant improvement in the service provided, or would even provide new services and therefore increase the number of server organizations involved on

  this type of system and the number of terminals installed.

  -2 - However, such an evolution will be a real success only if all the partners concerned derive an economic interest: better service for the user, increased traffic for the operator of the network; and most importantly, increased revenue for the service provider allowing it to amortize additional required investments such as an image host

quality.

  For example, in the case where the agency is an agency or a group of real estate agencies, it would be useful to be able to transmit to the holder of the terminal a photograph of the house for sale or rent, or a detailed plan and quoted of the apartment for sale. Many other uses could be described such as travel agencies, mail order etc ... The transmission of quality graphics raises a priori both problems of using transmission networks other than the telephone network switched

  standard and methods of payment of benefits.

  The present invention uses the digital information transmission network called ISDN in France, it is necessary to describe it briefly, this network is also described in detail in the CCITT standard I. In the switched telephone network, at least in France, the transmission of information is most often in digital form between the various telephone exchanges and the transmission of information is in analog form between each telephone and the central office to which it is connected. In the ISDN network the transmission of information is also digital between

  central office and telephone sets.

  Physically the connection between a central office and a telephone is made by two conductors of the type switched telephone network (PSTN). There are two types of subscription: A subscription says primary access and a subscription says basic access. The invention relates more specifically to basic access. In this type of subscription, the subscriber has three channels: two channels called channels B for the transfer of "useful" information and a channel called D channel which is a signaling channel used to transmit the necessary information including the establishment of communications and possibly the payment of communications. According to the current standard each channel B can transmit 64 kbits / second and channel D 16 kbits / second. An ISDN channel can operate in two different modes depending on how the terminal connected to the network is mounted. In the so-called "transparent" mode, the connected terminal receives the information in digital form. This is the normal way of connecting to the ISDN network. In the so-called "non-transparent" mode, the connected terminal receives the information in the form

  analogue, so as if it were connected to the standard PSTN.

  In addition, in the description that follows it will be necessary to understand

  the terms "non-graphic information" and "graphic information" or "quality graphic information" as follows. Information is called "graphic" or "quality graph" if this information can be developed on the screen of the terminal an image conforming to the standard CCIR ie having 720 x 575 pixels, each pixel being defined by 16 bits color information or more generally alphaphotographic information. The "non-graphic" information is the information that makes it possible to display on the screen of the terminal data or images that are not in conformity with the alphaphotographic presentation. These informations are, for example, typically "videotex", in France "alpha mosaic". The information is the ones

  are distributed by the standard TELETEL system.

  To overcome this drawback, an object of the invention is to provide a teleserver system for delivering quality images without requiring the establishment of a new physical distribution network and authorizing a payment method compatible with the TELETEL system and promoting the economic interests of each

partners.

  To achieve this goal the teleserver system, according to the invention, comprises at least one non-graphic information transmission center, a plurality of terminals for receiving information and connection means between said center and said terminals and it is characterized in that it further comprises a quality graphical information transmission center and that the connection means comprises the use of a digital network (ISDN) connecting said terminals to basic accesses, each basic access comprising two transmission channels B, and a signaling channel D, a first channel B being used in non-transparent mode for the transmission of non-graphic information and the second channel B being used in transparent mode for the transmission of quality graphic information, and in that each terminal comprises means for allowing the user of the terminal to control the transmission of said graphic information of quality in response to information received by the terminal via said channel B to

  transmission in non-transparent mode.

  It is thus understood that the Teleserver system does not require the introduction of any new means of transmission since the ISDN digital network is already developed and that it uses the normal telephone network as the basic physical transmission medium. On the other hand, thanks to the use of this type of digital information transmission (transparent mode) it is possible to give access to the teleserver system to organizations whose provision of services requires being able to transmit

  to the user images of a very high quality.

  In addition such a teleserver system is fully compatible with a conventional teleserver system of the type

TELETEL.

  According to a preferred embodiment, the terminal comprises means for storing the quality graphic information transmitted by the digital B-channel (transparent mode), means for interrupting the connection with said transmission centers, and means for suppressing said graphic information stored in response to

  the actuation of the interruption means.

  Thus the channel actually used in transparent (digital) mode is only used for a very short time corresponding to the transmission time of the information necessary for the definition of an image or a limited number of images. However, since the information relating to an image is "erased" at the end of a communication using the non-transparent B-channel the user can not misuse the system, ie beyond the price it paid, to build collections of images. According to another characteristic of the invention, the terminal comprises a device for reading / writing in a medium

264 1926

  -6- removable information capable of storing successive balances, to modify said balance according to

  charging signals received by said terminal.

  Other features and advantages of the invention

  will appear more clearly on reading the description

  following of several embodiments of the invention

  given as non-limiting examples. The description is

  refers to the accompanying drawing in which: Figure 1 shows the general organization of a teleserver system according to the invention; FIG. 2 shows in detail a terminal connected to the teleserver system according to the invention; FIG. 3 shows an embodiment variant of the terminal

of Figure 2.

  Referring first to Figure 1, we will describe the entire teleserver system according to the invention. It includes a number of servers or centers

  resignation. We find on the one hand servers SV1, SV2 ...

  which deliver non-graphical information or videotex, and servers SG1, SG2 ... which deliver information

  graphics. These servers are connected to the ISDN network.

  In this network were the telephone exchanges C1 and C2 as well as a first terminal T1 connected to the central C1 and a second terminal T2 connected to the central C2 by links LI and L2 of the ISDN type. The links L1 and L2 each define two data channels B and one D-channel

signaling.

  We will now refer to FIG. 2 to describe in detail a terminal according to the invention, for example the terminal T1 of FIG. 1. The line L1 is connected to a so-called type S interface circuit 10 in the system ISDN. At the output of the circuit 10 there is shown the lines 12, 14 and 16 respectively corresponding to the channels B1 and B2 and the D-channel. The line 12 is connected to an adapter circuit 18 of standard ISDN type which makes the B1 channel non-transparent, that is, able to transmit analog signals. The circuit 18 is connected to a standard TELETEL terminal. The terminal 20 is associated with a high-definition display screen 22 and a standard keyboard 24. The components 20, 22 and 24 form what is usually called MINITEL except for the

quality of the screen.

  Line 14 (channel B2) is connected to a standard compressor / decompressor circuit 26. The function of this circuit will be explained later. The circuit 26 is connected to a read / write / erase head 28 associated with a "hard" memory disk 30. The head is connected to the control circuit 32 of the screen 22. The channel B2 is transparent. Line 16 (channel D) is connected to a circuit 34 for processing the signaling information which flows in both directions via the D-channel. The terminal T1 also comprises a microprocessor 40 for managing all the components of the terminal. The microprocessor is connected to the control input 28a of the read / write / erase head 28. It is also connected to the keyboard 24, to the TELETEL terminal 20, to the processing circuit 34 and to an ISDN numbering circuit 42, itself connected to the processing circuit 34. In the embodiment represented in FIG. provided services is performed using an electronic memory card 44. For this a read / write device 46 is connected to the microprocessor 40. The

  card 44 is, for example, 'prepayment type telecarte.

  Its integrated circuit includes a programmable memory, each memory point corresponds to a charging unit. The reader 46 can read the memory points already written in the card and write new memory points as and when the consumption of charging units. Such a reader is well known as well as the particular procedures of dialogue between the card and the reader to verify the authenticity of the card and for

  change the available balance in the card's memory.

  This part of the terminal T1 will therefore not be described more

in detail.

  We will now describe how to use the terminal T1. The user turns on the terminal and introduces his card 44 in the slot 48 of the reader 46. It will be assumed that the card is genuine and has a sufficient balance. Using the keyboard 24 the user dials the number of the server to which he wants to connect. By

  example, it is a group of real estate agencies.

  Then it proceeds exactly as with a standard MINITEL via the Bl channel which is non-transparent. The charging pulses arrive at the circuit 34 via the channel D. They are transmitted to the microprocessor 40 which controls the reader 46 to "burn" a memory point of the card 44 to

each charging pulse.

  It will be assumed that the server to which the user has connected makes it possible to obtain, in addition to videotext information (non-graphics), graphic information, for example three apartment plans. Information (non-graphical) appears on the screen 22 to invite the user to consult these plans if he wishes. If this is the case, it dials on the keyboard 24 the appropriate command. The keyboard 24

  delivers to the microprocessor 40 a specific signal.

  The microprocessor 40 then generates the call number of the "graphic" server associated with the "vidiotex" server to which the terminal is already connected. This number is transmitted to the dialing circuit 42 and then to the processing circuit 34 D5 and sent to the network via the D-channel. The graphic information arrives back, via the transparent channel B2, to the compressor / decompressor circuit 26. The associated digital information and a standard CCIR image correspond, as already indicated, to 720 X 576 x 16 bits, or about 6.6 Mbit. The image server is provided with an image compressor which divides by 20 the number of bits of information necessary to define an image. The number of bits to be transmitted via the B2 channel is 330 kbits. Given the flow of the B channels this

  represents a usage time of the order of 5 seconds.

  Circuit 26 has the function of "decompressing the image".

  The graphic information received by the circuit 26 is stored on the disk 30 by means of the write head 28. At the same time the circuit 34 receives from the central office, via the channel D, the charging pulses. Upon receipt of each pulse the microprocessor 40 controls the card reader 46 to "burn" a memory point of the card. The card is therefore decremented by the TELETEL charging pulses and the ISDN charging pulses due to the transparent B-channel. The TELETEL pricing unit corresponds. 40 seconds of communication. The ISDN charging unit is a communication time that depends on the distance between the server and the terminal. When this distance is less than 50 km this duration is equal to 23 seconds. So we see that for the reception of four images it is sufficient to pay a single fee. The impact of ISDN pricing is therefore negligible compared to that of the

TELETEL pricing standard.

  When the user wishes to interrupt the connection with the server he enters the appropriate command using the keyboard 24. The communication is interrupted. When the microprocessor 40 receives the interrupt signal, it D5 controls the head 28 so that it erases on the hard disk all the information corresponding to the received images. FIG. 3 shows a second embodiment of the terminal T1 which differs from that of FIG. 2 only in the mode of determination of the amount of the payment to be made for the provision of service. According to the embodiment of FIG. 2, the terminal T1 receives pulses from

  charging corresponding to the TELETEL network and the ISDN network.

  It is these impulses that serve to decrement the balance stored in the user's card. According to the embodiment of FIG. 3, the charging elements are included in the terminal. For this, the terminal also comprises a charging memory 50 and a clock 52 which are connected to the microprocessor 40. The memory 50 contains a tariff table which comprises for the TELETEL system and for the ISDN system the duration of each charging unit. For ISDN, in the case of a transparent channel, the table uses the distance from the image server determined from the call number of the image server. From the time information and the data contained in the memory 50, the microprocessor 40 generates the TELETEL and ISDN charging pulses which are applied to the reader 46 as explained in FIG.

connection with Figure 2.

  It follows from the previous description that the system

  teleserver, according to the invention, satisfies the conditions that had been imposed. For the network operator the possibility of transmitting images must increase the number of service providers wishing to operate on these networks. In addition, the development of the ISDN network will benefit from the success of the TELETEL system. For service providers the transmission of images makes the service more attractive and therefore increases the number of communications. In addition, the consultation of the images increases the duration of the communication and therefore the amount of

  the fee paid to the service provider.

-12-

Claims (6)

  A teleserver system comprising at least one non-graphic information transmission center, a plurality of terminals for receiving information and connection means between said center and said terminals and characterized in that it further comprises a center transmission of graphical information-quality and in that the connection means comprise the use of a digital network (ISDN) connecting said terminals to basic accesses, each basic access comprising two transmission channels B , and a signaling D-channel, a first B-channel being used in non-transparent mode for transmitting non-graphics information and the second B-channel being used in transparent mode for transmitting quality graphics information, and in that each terminal comprises means for enabling the user of the terminal to control the transmission of said quality graphic information in response to information received by the terminal via said channel   Transmission B in non-transparent mode.   2. System according to claim 1, characterized in that each terminal comprises means for storing the graphic information transmitted by the B channel in transparent mode, means for interrupting the connection with said transmitting centers, and means for suppressing said graphic information stored in response to the actuation of the interruption means.   3. System according to any one of claims 1 and   2, characterized in that said terminal comprises a read / write device in a removable information medium capable of storing balances -13-. successive installments, to modify the said balance according to received charging signals.   4, System according to any one of claims 1 to   3, characterized in that said terminal receives first charging signals as a function of the transmission of information by the non-transparent mode B channel and of the second charging signals as a function of the transmission of information by   digital channel by canl B in transparent mode.   5. System according to claim 4, characterized in that said charging signals are transmitted by said D channel signaling.   6. System according to any one of claims 1 to   Characterized in that said terminal comprises means for generating itself charging signals for the transmission of graphic information and charging signals for the transmission of data. non-graphic information.